1. Field of Invention
The present invention relates to aluminum containing astringent gel compositions and a method for their use.
2. Description of the Prior Art
Aluminum acetate solution, also referred to as Burow's solution, has long been known and used as an astringent when applied to the skin. It is approved for use by the US Food and Drug Administration dispensed as a 2.5 to 5% by weight clear solution of aluminum acetate (triacetate) for use as a wet dressing, compress or soak for relief of inflammatory conditions and minor skin irritations. Burow's solution may be prepared by reacting aluminum sulfate, calcium carbonate and 6 molar acetic acid to form aluminum subacetate topical solution (also referred to as monobasic aluminum diacetate) and a precipitate of calcium sulfate. The calcium salt precipitate is removed by filtration and the filtrate is converted to aluminum acetate solution (Burow's solution) by the addition of acetic acid. Other methods for the preparation of Burow's solution include treatment of dibasic aluminum monoacetate with glacial acetic acid and the methods disclosed in U.S. Pat. Nos. 2,824,042 and 2,827,420.
It is generally recommended that Burow's solution be freshly prepared before use because it tends to become unstable over prolonged periods of standing and tends to lose its potency. This loss in potency is due to the precipitation of the more basic aluminum salts.
It is also common in the prior art to prepare mediciment formulations in the form of a gel for application to the skin. For example, U.S. Pat. No. 3,856,941 discloses an astringent gel formulation based on a mixture of astringent salts such as aluminum and zinc, zirconium or magnesium salts, and further including a gelling agent and a glycol. The patent indicates that the stability of the formulation is enhanced by combining two or more such salts and formulating them into a gel at relatively high concentrations of about 13 to 18% by weight.
However, the requirement of the usage of such a mixture of salts at relatively high concentration in the gel formulation to achieve stability can give rise to other problems including tolerance or irritation of the skin to such preparations due to the high salt concentration.
Accordingly it is an object of this invention to provide a formulation of Burow's solution in gel form for convenient application to the skin.
Another object is to provide a formulation of Burow's solution as a gel which remains stable over extended periods of storage.
Yet another object of the invention is to provide an astringent formulation for application to the skin, particularly to the hands, for relief of inflammatory skin conditions, erythema. chapping and minor ulcerations of the skin.